Automatic lock for extension-ladders.



H, C. RUSSELL. AUTOMATIC LOGKqFOB EXTENSION LADDERS. APPLICATION FILED NOV. 18,'1913. 1 1 1 3,836, Patented Oct. 13, 1914.

ATTORNEY IIII IIIIIII III INVENTOR WITNESSES www HARRY c. RUSSELL,` or NAsHUAj, `ivnvvfini-MrSHIRE;

` AUTOMATIC LOCK Fon EXTENsiomLADnERs.

Specification of Iretters Patent. ltelited Oct, 13, 1914.

` Applicationineanovember 18,1913. .seriainagsoigaa T0 all whom 'it may concern: y

Be it known that I, HARRY C. RUSSELL, a citizen of the UnitedStates, residing at Nashua, in the countyof Hillsboro and State of New Hampshire, have invented a new and useful Automatic Lock `for .Exten-y sion-Ladders, of which the following is a speciiication.

The invention relates to improvements inl automatic locks for extension ladders.

The object of the present invention is .tol`

improve the construction of automatic locks for extension ladders,v more `especially the manner of mounting and housing the pivoted hook, and to provide a simple and ineXf`` pensive device of strong and durable con-` struction adapted to brace and strengthen` the extension ladder at the points where.y

the lock is applied.

With these and other objects in view, the

invention consists in the construction and novel combination of parts hereinafter fully described, illustrated in the accompanying drawing, and pointed out in the claimhereto appended; it being understood thatvarious changes in the form, proportion, size and minor details of construction, within the scope of the claim, may be resorted to with` out departing from the spirit or sacrificing any of the advantages of the invention.

In the drawing: Figure 1 is a side elevation of an automatic lock, constructed in accordance with this'invention and shown applied to an extension ladder, the pivoted hook being in engagement with one of the rungs of the base ladder. Fig. 2 is a similar view partly in section, the engaging portion of the hook being swung backwardly from` its engaging position. Fig. 3 is a longitu.- dinal sectional view, taken substantially on the line 3 3 of Fig. 1. Y

Like numerals of reference designate corresponding parts in all the figures of the drawing.

In the accompanying drawing in which is illustrated the preferred embodiment of the invention, 1 designates a gravity acting hook pivotally mounted on a slidablel extension ladder 2 within a housing 3 thereof and arranged to engage the rungs 4 of a base ladder 5 to which the extension ladder is slidably connected in the usual manner. The housing 3 consists of a bar of metal preferably of a width slightly less than the width of the side bar or piece of the extension lad der 2 and having its terminals bent inwardly g at right angles toform abutting end por` tions 6,`whichfit against the outer face of thefadjacent side bar or piece of the eXten- `sion ladder 2 and space the body portion of the b ar from the ladder, as clearlyshown in Fig. 3 ofthe drawing. The housing 3, which is made `of relatively heavy material inbrder. tojbra-ce the extension ladder at thepoint'where. the automatic lock is applied, andy secured to the adjacent side of the eXtensionladder 2 by means of central and end bolts 7 fand 8,*.piercing the housing ...atthe center` of thesaine and at theupper and" lowerfp'oitions thereof. The central bolt, which is relatively heavy, forms a pivot for-the gravity hook 1, washers 9 being preferably arranged at theinner and outer faces ofthe gravity hook to space the same from `the side bar or piece of the extension ladder 2 and 4alsogfmm the housing, whereby the gravity hookfis `permitted to swing freely on the pivot bolt. 'The bolts extend entirely `through the side bar or piece of the eXten sion ladder andare preferably provided at their inner ends/.with nuts, the heads of the end bolts being countersunk in the metal of the housing. g, y

The gravity hook is provided at a point intermediate of its ends with an opening 10 for the `central pivot bolt, and its upper portion 11 is enlarged and bulged rearwardlyand it forms a weight for throwing the lowerportion forwardly into the plane of the rungs of the base ladder. y The gravity hook isprovided at its lower end with a rung-receiving recess 12, and it has arms or bills 18 and 14 at the front and back of the recess,the arm 13 being located above and the arm 14 beneath an engaged rung, as

When the extension ladder is movedupwardly on `the baseladder, the gravity hook `will, pass the rungs 4, being swung backwardly by the same, as illustrated in Fig. 2 ofthe drawing, the backward movement of the engaging portion of the gravity hook` being limited by the lower end bolt. The upper end bolt is also adaptedv to limit the upward and rearward swing of the engaging end of the gravity hook, so that the latter cannot swing backwardly too far either at the upper or lower portion of the housing and turn completely over to an inoperative position. By this construction, the gravity hook is also maintained by its weighted arm 4 in proper` position for automatic engage- Whatis claimed is:-

ment with av rung and free play of--thefhook v on the pivot boltzis gpermittedj, The ;hool` is engaged with a rung by raising the eXtension ladder 'suiiicientlyto earrytheliookfto a point above the rung to be engaged and A the extension ladderqis then lowered :into1 engagement with the rung, which is received between the projecting arms or bills 13 Land 14.

The means for'mountingsthe gravity 'hook substantially houses the samel and, rein-v vtorces or braces-the extension ladder andat ythesame time is devoid of any projections, :which 4might `catch on .the Clothes of A'the workingmenand causea fall.

The 'combination with an yextension ladder, of ya housing consisting Aof a metallic bar extending longitudinally oflone side of the extension ladder and having its termi-l (nal :portions bent' vinwardlyr at, right angles .and abutting against theezztension dadder .and spacing the tbody `portion kof @the @bar ing portion, the end bolts forming stops within the housing for limiting the swing of the sa1d lower engaging portlon of the hook, whereby the latter 1s ,maintained 1n proper ,position for automatic'engagement with the rung 'of a base ladder, said bar forming a liousingfor the hookin yboth its upright and inverted vvertical positions.

"In testimony that "I claim the foregoing as my own, I have hereto aiiixed my signa- "ture nthejpresence of two witnesses.

`HARRY C. RUSSELL.

Witnesses:

"FRED 1T. RUSSELL, l NELLIE 'L. RUSSELL.

.Copiesrofithisipatent mayibe obtained-fornire cents-reach, byaddressing the Commissioner of Patents Washington, 20.16. 

